Get to know the differences between Plastic Injection Molding and Plastic Extrusion

Plastic injection molding and plastic extrusion are both popular manufacturing processes used to create plastic parts, but they differ significantly in their methods and applications. While they both produce high quality flurorpolymer parts, plastic injection molding produces three-dimensional shapes vs. plastic extrusion produces linear, two-dimensional shapes.

 

 

 

Process:

• Injection Molding:  This process involves injecting molten plastic material into a mold cavity, where it cools and solidifies to form the desired shape. The mold typically consists of two halves and the material is injected under high pressure.
• Extrusion:  In extrusion, plastic material is melted and forced through a die tocreate a continuous profile. The die gives the plastic its desired shape,and the material is cooled and solidified as it exits the die.

Equipment:

•  Injection Molding:  Injection molding machines consist of a hopper where the plastic pelletsare fed into a heated barrel. Inside the barrel, the pellets melt and are injected into the mold cavity.
•  Extrusion:  Extrusion machinery includes an extruder, which is essentially a long barrel with a screw conveyor inside. The plastic pellets are fed into one end of the extruder, where they are heated, melted, and forced through a die at the other end.

Applications:

• Injection Molding:  This process is commonly used for producing intricate and complex parts with high precision and repeatability. It’s used in industries such as aerospace/defense, industrial, electronics, and medical devices.
• Extrusion:  Extrusion is often used to create continuous lengths of plastic profiles or sheets with a consistent cross-section. It’s employed in applications such as pipes, tubing, window frames, and traffic control items.

Complexity and Cost:

•  Injection Molding:  Tooling costs for injection molding can be higher due to the need for precision molds, especially for complex parts. However, once the mold is made, the cost per part can be relatively low.
• Extrusion:  Extrusion tooling costs are generally lower compared to injection molding, especially for simple profiles. However, the process may not be as suitable for highly complex shapes.

Material Variation:

• Injection Molding:  A wide range of thermoplastics such as FEP, PFA, Torlon, etc., can be used in injection molding, allowing for flexibility in material selection.
• Extrusion:  While extrusion also supports various fluoropolymer materials, the process is particularly suited for thermoplastics that can be melted and reshaped repeatedly.

In summary, while both plastic injection molding and plastic extrusion are versatile manufacturing processes used in the plastics industry, they each have applications suited to different types of products and applications.

Plastic injection molding is best applied to three-dimensional shapes, while plastic extrusion is best suited for two-dimensional shapes.

For more information on the best molding application for your project, please contact Rich Reed, Vice President – Custom, at [email protected] or visit our website at www.performanceplastics.com.